1. Field of the Invention
This invention relates to volumetric feeders, and more specifically, to a volumetric feeder for a rotary furnace.
2. Description of the Prior Art
Prior art rotary retort furnaces are faced with the problem of feeding metal parts therein without either damaging the metal parts or allowing too much outside atmosphere to enter. A typical solution to this problem is disclosed in the patent issued to Charles W. Wolfe, U.S. Pat. No. 3,280,993. A spiral loading chute which feeds metal parts into the retort furnace at a predetermined rate is disclosed therein. A gate mounted in the spiral chute selectively passes materials therethrough while it seals off the furnace from the outside air.
One major difficulty with this approach is that the batch delivered to the furnace is frequently of an irregular volume. This is a problem because the metal parts act like a heat sink and unless they are evenly loaded into the spiral retort uneven temperature distribution may result causing the quality of the output product to vary.
Another solution to the problem is disclosed in the patent to William I. Bayly, U.S. Pat. No. 3,878,947. The disclosure therein overcomes some prior art shortcomings by providing a measuring station where the amount of work pieces may be measured prior to being fed into the furnace. However, since a single door is used to permit the work pieces to enter the furnace, the outside atmospheric air is permitted to enter the furnace therewith, thereby varying the concentration of the oven gases and the temperature causing an inferior product to be produced.